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The magnetic properties of columnar Co films on SiO[sub 2] substrates fabricated by oblique-angle incident thermal evaporation at room temperature were systematically examined by multiple techniques, including magnetic force microscopy (MFM), magneto-optical Kerr effect (MOKE), and scanning electron microscopy (SEM). Films with thickness ranging from 50 to 500 nm were deposited at the incident angles θ (with respect to substrate normal) from 0° to 85°. For films with thickness of ∼500 nm, the SEM shows the column tilt angle β increases as the θ angle increases and β < θ. The MFM images show that for 55° < θ < 75°, stripe domains are formed and are nearly parallel to the direction of incident vapor beam. The hysteresis loops obtained from MaKE show that along the direction perpendicular to the incident vapor beam the coercivity H[sub c] stays almost constant for all θ angles and the squareness decreases as the θ increases. This is in contrast to the increase of H[sub c] and the increase of squareness in the direction parallel to the incident vapor beam for θ > 60°. The result implies that for θ > 60°, the axis parallel to the incident beam behaves more like the in-plane easy axis. These magnetic anisotropies are correlated to the angular-dependent columnar structure of Co films. [ABSTRACT FROM AUTHOR]

Abstract: Using two consecutive regarding glancing angle depositions at different deposition angles and with different materials, a WO3-core TiO2-shell nanostructure has been fabricated and has photocatalytic enhancement up to 70 times over amorphous single layer TiO2 thin films, 13 times enhancement over crystalline (anatase) TiO2 thin films, and 3 times enhancement over c-TiO2/a-WO3 two-layer thin films, with much less the load of TiO2. We believe that the mechanism for the photocatalytic enhancement is from the increased density of charge separated electron-hole pairs aided by the WO3 layer, the interfacial area between the two-layers, and the large surface area from the porous nanostructure. [Copyright &y& Elsevier]

By assuming the H diffusion coefficient and H adsorption rate to be exponentially and linearly dependent on concentration, a physical model is developed to predict the hydrogenation process of Mg nanoblades. The predicted H uptake curves agree well with the experimental data from V-coated Mg nanoblades. The obtained H diffusion coefficients in MgHx between Mg and MgH2 have nearly three orders of magnitude variation. The characteristic time of H surface adsorption is longer than that of H diffusion in Mg but shorter than that in MgH2 for 100 nm thick nanoblades. A hydride shell is not formed during the hydrogenation. [ABSTRACT FROM AUTHOR]

The dynamics of spreading of a water drop on a vertically aligned Si nanorod array surface is studied with a fast charge coupled device camera. Four dynamic spreading regimes are identified, with a precursor rim advancing ahead of the contact line. The diameters of the precursor rim Dp, the precursor length δ, and the contact line Dc obey dynamic scaling laws, Dc,p∝tnc,p/2, with nc≈0.216 and np≈0.272, and δ≈t1/2. The exponents do not vary significantly with the nanorod height and are consistent with the dynamic spreading behavior on a rough or porous surface. [ABSTRACT FROM AUTHOR]

Abstract: During the lithiation of a Si anode from pure Si to fully lithiated alloy, the volume expands four times and modulus varies by several tens of times. Thus, the Li-ion diffusion and the stress evolution can be strongly coupled, which may play a significant role in determining the anode performance. In this work, we present a theoretical study of the fully coupled diffusion and stresses in a nonequilibrium Li by taking into account the effects of composition-dependent modulus, finite concentration, and boundary constraint. The Li-ion diffusion and induced stresses in a bilayer Cu-coated Si anode at the nanometer scale is examined to show these important effects. The transient stress-assisted diffusion problem is solved numerically by a finite difference method, whilst the stress field is obtained analytically. It is shown that the modulus variation with composition plays a mild role in the Li-ion diffusion. In order to account for the finite concentration effect, a nonlinear flux equation is introduced that describes the Li-ion diffusion over the full range of concentration from dilute to near-saturation state in a unified, symmetric manner. The finite concentration effect is significant, especially during the early delithiation process. The boundary constraint effect is found to play an intriguing role in the chemical diffusion. The bending stress results in a resisting force to Li-ion flow preventing effectively the Si anode from full lithiation. The constraint effect is significant for a wide range of Cu thickness. [Copyright &y& Elsevier]